This invention relates to a method of aligning a vehicle sensor, which is arranged on a motor vehicle and is swivelable about at least one axis, in the direction of an attention angle determined as a function of the actual driving situation.
As a rule, modern motor vehicles have a plurality of vehicle sensors. These may also be used for the detection of objects in the vehicle surroundings. Vehicle sensors of many different operating principles (radar, lidar, infrared, ultrasound, etc.) are known. Most such vehicle sensors, particularly those designed for a large range, are limited to a relatively narrow aperture angle (+/−15 degrees) around a main beaming direction. Individual vehicle sensors can therefore often only cover a relatively small receiving range. When several sensors interact for covering larger receiving ranges, the number of required sensors will increase while the aperture angle of the sensors decreases.
In order to increase the effective receiving range of vehicle sensors, it is therefore known to use swivelable vehicle sensors. From European patent document EP 1 323 570 B1, it is known to align a vehicle sensor by swiveling on a motor vehicle in a time variable manner such that the probable driving route of the motor vehicle is covered as well as possible at any time. Further, it is known from German patent document DE 103 49 210 A1 to detect a potentially dangerous object and to control the swiveling motion of a swivelable vehicle sensor as a function of the characteristics of the dangerous object and of the alignment of the motor vehicle with respect to the latter. However, the above-mentioned devices and methods have the disadvantage that significant foreknowledge concerning potential danger still remains unutilized. A swivelable vehicle sensor is therefore not used in an optimal fashion, and recognizable danger may not be reliably detected.
It is an object of the invention to create a simple method by which the practical benefit of swivelable vehicle sensors is further increased.
The methods of the above-mentioned type known from the state of the art frequently aim at a covering of future locations by the sensor, that is, the covering of the probable driving route, of the motor vehicle by the sensor. However, this approach does not consider the fact that possibly dangerous objects, particularly other traffic participants with which the motor vehicle could collide, frequently are moving themselves. The speed of the dangerous objects may even be far higher than that of the motor vehicle itself. Particularly at junctions and intersections, the sensory monitoring of the probable driving route alone is therefore informative only to a limited extent.
As a rule, not all data are available that would be required in order to determine the existence and the movement of all dangerous objects in the environment of the motor vehicle. However, in many traffic situations, at least the traffic routes (for example, roads, streets, exits, lanes, bike paths, pedestrian paths) are known on which the dangerous objects could approach the vehicle. The invention is therefore based on the idea of an improved monitoring of these traffic routes.
According to the invention, the existence of a traffic route leading into the probable driving route of the vehicle is detected first. The vehicle sensor will then be swiveled such that its receiving range at least partly contains or covers the traffic route leading into the probable driving route of the motor vehicle. The attention angle, into whose direction the swivelable vehicle sensor is aligned, or the desired value of the attention angle in a control system or an automatic control system, will be correspondingly selected for this purpose.
Thus, in contrast to the state of the art, in the case of the method according to the invention, the swivelable vehicle sensor is surprisingly, at least in certain driving situations, specifically not used for monitoring the probable driving route of the motor vehicle but is aligned in a direction in which, including on the basis of foreknowledge concerning the surrounding traffic routes (such as the position and the course), potentially dangerous objects could be located—specifically on traffic routes leading in to the driving route.
In the sense of the invention, leading-in traffic routes are mainly all roads, streets, bridges, exits, etc. on which potentially dangerous objects, for example, another traffic participant, can approach the driving route of the motor vehicle. Individual driving lanes of such roads may also be traffic routes in the sense of the invention. If it is known, for example, that the motor vehicle is moving straight ahead on a first road and a second road leading laterally into the first road has two driving lanes which are typically traveled in opposite directions, it is contemplated to consider only the driving lane of the second road on which traffic participants typically approach the first road a traffic route in the sense of the invention (when motor vehicle traffic takes place on the right side of the road, usually the right traffic lane viewed in the driving direction).
The presence of leading-in traffic routes is preferably detected by use of map data of a navigation system. However, it may also be detected by use of independent vehicle sensors, for example, by a vehicle camera.
A leading-in traffic route in the sense of the invention may always either have the right of way or not have the right of way. The primary decisive factor is whether there is the possibility that a dangerous object on the respective traffic route is approaching the motor vehicle such that it could collide with the latter. Having the purpose of a particularly good detection of danger, the method according to the invention may be implemented such that, independent of any traffic control, any leading-in traffic route is monitored with respect to approaching dangerous objects. For example, even traffic participants may be detected early by the vehicle sensor, which could critically approach the motor vehicle only if they were to drive in the wrong direction on a one-way street or overlook a stop sign.
In contrast to such a safety-oriented interpretation, according to a preferred embodiment of the invention, foreknowledge concerning traffic control, particularly at the intersections of traffic routes, is also used for detecting the presence of leading-in traffic routes in the sense of the invention. Thus, for example, known right-of-way rules and the presence of traffic lights as well as their switching state may be taken into account. In this manner, for example, branching-off one-way streets can be excluded as leading-in traffic routes in the sense of the invention. Also, a street may be disregarded which will probably not be traveled by the motor vehicle and, in addition, has no right of way. As a result of foreknowledge of existing right-hand traffic, as a rule, the right-hand branch of a crossroad, into which the motor vehicle will probably turn off to the right, may also be excluded. When detecting all relevant leading-in traffic routes, country-specific regulations and behaviors (such as the German turning-off vs. the U.S. American turning-off while “joining the flow of traffic”) can also be taken into account.
The foreknowledge concerning traffic control may, for example, originate from map data of a navigation system or may be available as additional information to such map data. Information concerning traffic control may be received by a motor vehicle, where the method according to the invention is used, also by way of teleservices and/or ad hoc networks which are established for the communication with other vehicles or stationary remote stations. Under certain circumstances, other traffic signs and/or traffic lights may be detected by camera and interpreted as an alternative or in addition.
In order to be able to determine which traffic routes lead into the probable driving route of the motor vehicle, it may be necessary or desirable—depending on the embodiment of the method according to the invention—that this probable driving route is known first. Preferably, the driving route of the motor vehicle is determined by the operating or switching state of a device for indicating the driving direction. It can also be determined by a route planned by a navigation system. Furthermore, vehicle sensors, for example, for detecting the steering angle, can be used for determining the probable driving route. A monitoring of the driver or a monitoring of the driver's behavior may also be performed for the purpose of recognizing his intention. Probabilistic and/or frequency-based approaches can also be used for determining the probable driving route. It can, for example, therefore be assumed that the driver approaching an intersection will travel a driving route which he has typically driven at the same time of day over a compared time period of several months. If different data are to be included in the determination of the planned driving route, intermediate results can in each case be calculated and compared with one another by way of a plausibility check.
The method according to the invention may also be advantageous in driving situations in which the probable driving route is not known or is not known with certainty. Thus, the knowledge of the probable driving route is therefore not a compelling prerequisite for the applicability of the method according to the invention. When the probable driving route is not known or is not known with certainty, for example, as a preventive measure, the respective leading-in traffic routes for all conceivable driving routes may be monitored. A simple hypothesis (for example, a straight-ahead drive) for the probable driving route can also be used. As a result, for example, all traffic routes which lead into the road actually traveled by the motor vehicle are to be considered to be leading-in traffic routes in the sense of the invention. The sequence of a sequential monitoring of leading-in traffic routes for several conceivable driving routes and/or the thoroughness of the respective monitoring may be oriented according to which of the conceivable driving routes is the most probable.
Even when several traffic routes are to be monitored for a single probable driving route, these will preferably be monitored sequentially. The sequence and/or the thoroughness of the respective monitoring may, for example, be determined according by which one of several conceivable driving routes leads first into the probable driving route.
The method according to the invention is advantageous particularly at intersections and side road crossings. When, for example, the motor vehicle approaches at a right angle a road that has the right of way and wants to turn into that road toward the right, according to the invention, the vehicle sensor can be aligned with the arm of the right-of-way road leading into the planned driving route from the left and can monitor this arm. In this manner, it can be checked whether a traffic participant is approaching from the left who has the right of way. The driver of the motor vehicle can then, for example, be warned.
For the exchange of information (for example, the utilization of sensor and map data and the output of a warning), the method according to the invention preferably communicates with other methods, particularly the method of detecting the environment and the method of assisting the driver, which are implemented in the same motor vehicle.
In order to be able to align the swivelable vehicle sensor in the case of the method according to the invention such that the leading-in traffic route is monitored in the desired fashion, the attention angle suitable for this purpose or a suitable variation in time of the latter has to be determined. For this purpose, the relative alignment of the motor vehicle with respect to the leading-in traffic route, as required, also the relative distance of the motor vehicle from the leading-in traffic route is of special significance. In principle, these quantities or their variation in time can be determined in many different fashions. According to a preferred embodiment of the present invention, the relative alignment of the motor vehicle with respect to the leading-in traffic route is determined by means of a determination of the absolute motor vehicle position and by means of map data of a navigation system.
However, as an alternative, the relative alignment of the motor vehicle with respect to the leading-in traffic route may also be determined by independent vehicle sensors. In this case, the independent vehicle sensors used for this purpose may comprise individual systems or several systems on the basis of radar, lidar, ultrasound, inertial platforms, gyroscopic sensors, terrestrial magnetic field sensors, as well as cameras (optical, near infrared, far infrared).
The two above-mentioned methods for the determination of the relative alignment of the motor vehicle with respect to the leading-in traffic route, if necessary, may also be mutually combined, for example, by a multi-stage approach or by the parallel calculation of partial results.
The determination of the relative alignment of the motor vehicle with respect to the leading-in traffic route can take place directly with the detection of the presence of the leading-in traffic route or may take place uncoupled from the latter. Correspondingly, also, for example, the presence of a leading-in traffic route can first be detected on the basis of map data, whereas the relative alignment of the motor vehicle with respect to the traffic route is determined in a camera-based manner.
As a rule, the method according to the invention will have the result that the vehicle sensor is not set to an attention angle that is constant with respect to time but to an attention angle that is variable with respect to time, because the movement of the motor vehicle with respect to the globally stationary traffic route requires a corresponding adaptation of the alignment of the vehicle sensor. This adaptation can take place while keeping pace with a correspondingly high updating rate. When the future driving route is at least partially known and/or predictable, for a high-quality and/or highly dynamic control of the swiveling motion, however, a variation in time can also be calculated ahead of time in a model-based manner for the attention angle.
In principle, only those parts of a leading-in traffic route which can be seen from the actual position of the vehicle sensor can be monitored by the method according to the invention. This will, as a rule, not be the entire traffic route but only an end of the traffic route facing the motor vehicle. Depending on the aperture angle of the vehicle sensor, it is also contemplated that, in certain driving situations, the monitoring of such an end of a leading-in traffic route cannot take place completely or reliably by the alignment of the vehicle sensor to a certain attention angle. This applies particularly in the case of a very narrow aperture angle of the vehicle sensor and a short distance from the leading-in traffic route or in the case of an extremely curved leading-in traffic route (such as rotary traffic). This problem can be solved in different fashions. For example, the monitoring can be limited to the part of the leading-in traffic route which is spatially the closest to the motor vehicle. The attention angle would then be selected such that the receiving range of the vehicle sensor resulting from the alignment in the direction of the attention angle contains the part of the traffic route leading into the probable driving route of the motor vehicle that is situated closest to the motor vehicle. However, an alignment to the part of the leading-in traffic route situated the closest may also take place first, in order to subsequently swivel the vehicle sensor to more remote parts. Thus, a larger part of the leading-in traffic route could be effectively monitored than the part that can be monitored in the case of a momentary observation.
The sensory monitoring of the vehicle environment according to the invention can also be distributed to several vehicle sensors. Correspondingly, certain responsibilities may arise for an individual vehicle sensor. In such a further development of the method according to the invention, the vehicle sensor will be aligned with a traffic route leading into the probable driving route of the motor vehicle only if it responsible for its monitoring. For example, a first swivelable vehicle sensor arranged on the right vehicle side may be responsible only for the monitoring of traffic routes which lead into the probable driving route of the motor vehicle from the right, while a second swivelable vehicle sensor arranged on the left vehicle side is responsible for monitoring traffic routes which lead into the probable driving route of the motor vehicle from the left.
Although a characteristic feature of the invention is the fact that a swivelable vehicle sensor is at least temporarily specifically not used for a monitoring of the probable driving route of the motor vehicle, the application of the method according to the invention definitely does not exclude the use of the swivelable vehicle sensor also temporarily, as required, even predominantly with respect to time, for a monitoring of the probable driving route of the motor vehicle (or for the monitoring of another direction, for example, the direction of the longitudinal vehicle axis). According to a preferred embodiment of the present invention, a particularly good utilization of the swivelable vehicle sensor is achieved in that, whenever no leading-in traffic route exists in the environment of the vehicle, its attention angle is selected such that the receiving range of the vehicle sensor resulting from the alignment in the direction of the attention angle largely contains the probable driving route of the motor vehicle. In the case of an above-described distribution of responsibility, the attention angle can always be selected such that the resulting receiving range largely contains the probable driving route of the motor vehicle when no leading-in traffic route, which falls into the range of responsibility of the respective vehicle sensor, is present in the environment of the motor vehicle.
Under certain circumstances, the efficiency of the method according to the invention can be increased when only those traffic routes are detected as leading-in traffic routes in the sense of the invention or are monitored as such which lead into the part of the future driving route which the motor vehicle will cover within a certain future time period (for example, within the following 15 seconds). The computing expenditures to be carried out by an arithmetic logic unit for the method according to the invention can thereby be reduced. Premature warnings to the driver can be avoided. A vehicle sensor, which is also used for the monitoring of the probable driving route of the motor vehicle, can be used for this purpose for a longer period of time.
The invention can already be used for controlling a vehicle sensor swivelable about a single axis but, without any problem, can be expanded to vehicle sensors swivelable about several axes. The monitoring of leading-in traffic routes can be further improved by a skillful controlling of a vehicle sensor swivelable about several axes. For example, inclinations of the motor vehicle (for example, as a result of loading) and/or slopes of the driving route of the motor vehicle as well as therefore also of the leading-in traffic routes can be compensated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.